Upload
others
View
4
Download
0
Embed Size (px)
Citation preview
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 1
Tables for Group Theory
By P. W. ATKINS, M. S. CHILD, and C. S. G. PHILLIPS
This provides the essential tables (character tables, direct products, descent in symmetry and
subgroups) required for those using group theory, together with general formulae, examples,
and other relevant information.
Character Tables:
1 The Groups C1, Cs, Ci 3
2 The Groups Cn (n = 2, 3, …, 8) 4
3 The Groups Dn (n = 2, 3, 4, 5, 6) 6
4 The Groups Cnv (n = 2, 3, 4, 5, 6) 7
5 The Groups Cnh (n = 2, 3, 4, 5, 6) 8
6 The Groups Dnh (n = 2, 3, 4, 5, 6) 10
7 The Groups Dnd (n = 2, 3, 4, 5, 6) 12
8 The Groups Sn (n = 4, 6, 8) 14
9 The Cubic Groups: 15
T, Td, Th
O, Oh
10 The Groups I, Ih 17
11 The Groups Cv and Dh 18
12 The Full Rotation Group (SU2 and R3) 19
Direct Products:
1 General Rules 20
2 C2, C3, C6, D3, D6, C2v, C3v, C6v, C2h, C3h, C6h, D3h, D6h, D3d, S6 20
3 D2, D2h 20
4 C4, D4, C4v, C4h, D4h, D2d, S4 20
5 C5, D5, C5v, C5h, D5h, D5d 21
6 D4d, S8 21
7 T, O, Th, Oh, Td 21
8 D6d 22
9 I, Ih 22
10 Cv, Dh 22
11 The Full Rotation Group (SU2 and R3) 23
The extended rotation groups (double groups):
character tables and direct product table 24
Descent in symmetry and subgroups 26
Notes and Illustrations:
General formulae 29
Worked examples 31
Examples of bases for some representations 35
Illustrative examples of point groups:
I Shapes 37
II Molecules 39
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 2
Character Tables
Notes:
(1) Schönflies symbols are given for all point groups. Hermann–Maugin symbols are given for
the 32 crystaliographic point groups.
(2) In the groups containing the operation C5 the following relations are useful: 12
12
12
12
(1 5 ) 1·61803 2cos144
(1 5 ) 0·61803 2cos72
1 1 –1
1 2cos72 2cos144 1
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 3
1. The Groups C1, Cs, Ci
C1
(1)
E
A 1
Cs=Ch
(m) E σh
A′ 1 1 x, y, Rz x2, y
2, z
2, xy
A″ 1 –1 z, Rx, Ry yz, xz
Ci = S2
(1)
E i
Ag
1 1 Rx, Ry, Rz x2, y
2, z
2,
xy, xz, yz
Au 1 –1 x, y, z
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 4
2. The Groups Cn (n = 2, 3,…,8)
C2
(2)
E C2
A 1 1 z, Rz x2, y
2, z
2, xy
B 1 –1 x, y, Rx, Ry yz, xz
C3
(3)
E C3 2
3C
ε = exp (2πi/3)
A 1 1 1 z, Rz x2 + y
2, z
2
E
*
*
1
1
(x, y)(Rx, Ry) (x2 – y
2, 2xy)(yz, xz)
C4
(4)
E C4 C2 34C
A 1 1 1 1 z, Rz x2 + y
2, z
2
B 1 –1 1 –1 x2 – y
2, 2xy
E
1 i 1 i
1 i 1 i
(x, y)(Rx, Ry) (yz, xz)
C5 E C5 25C
35C 4
5C ε = exp(2πi/5)
A 1 1 1 1 1 z, Rz x2 + y
2, z
2
E1
2 *2 *
* *2 2
1
1
(x,y)(Rx, Ry) (yz, xz)
E2
2 * *2
**2 2
1
1
(x2 – y
2, 2xy)
C6
(6)
E C6 C3 C2 2
3C 5
6C ε = exp(2πi/6)
A 1 1 1 1 1 1 z, Rz x2 + y
2, z
2
B 1 –1 1 –1 1 –1
E1
* *
* *
1 1
1 1
(x, y)
(Rz, Ry) (xy, yz)
E2
* *
* *
1 1
1 1
(x
2 – y
2, 2xy)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 5
2. The Groups Cn (n = 2, 3,…,8) (cont..)
C7 E C7 27C 3
7C 47C 5
7C 67C ε = exp (2πi/7)
A 1 1 1 1 1 1 1 z, Rz x2 + y
2, z
2
E1
2 3 *3 *2 *
* *2 *3 3 2
1
1
(x, y)
(Rx, Ry) (xz, yz)
E2
2 *3 * 3 *2
*2 3 * *3 2
1
1
(x2 – y
2, 2xy)
E3
3 * 2 *2 *3
**3 *2 2 3
1
1
C8 E C8 C4 C2 34C
38C
58C
78C ε = exp (2πi/8)
A 1 1 1 1 1 1 1 1 z, Rz x2 + y
2, z
2
B 1 –1 1 1 1 –1 –1 –1
E1
* *
* *
1 i 1 i
1 i 1 i
(x, y)
(Rx, Ry) (xz, yz)
E2 1 i 1 1 1 i i i
1 i 1 1 1 i i i
(x
2 – y
2, 2xy)
E3
* *
* *
1 i 1 i
1 i 1 i
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 6
3. The Groups Dn (n = 2, 3, 4, 5, 6)
D2
(222)
E C2(z) C2(y) C2(x)
A 1 1 1 1 x2, y
2, z
2
B1 1 1 –1 –1 z, Rz xy
B2 1 –1 1 –1 y, Ry xz
B3 1 –1 –1 1 x, Rx yz
D3
(32)
E 2C3 3C2
A1 1 1 1 x2 + y
2, z
2
A2 1 1 –1 z, Rz
E 2 –1 0 (x, y)(Rx,, Ry) (x2 – y
2, 2xy) (xz, yz)
D4
(422)
E 2C4 22 4( )C C 2C2
' 2C2
"
A1 1 1 1 1 1 x2 + y
2, z
2
A2 1 1 1 –1 –1 z, Rz
B1 1 –1 1 1 –1 x2 – y
2
B2 1 –1 1 –1 1 xy
E 2 0 –2 0 0 (x, y)(Rx, Ry) (xz, yz)
D5 E 2C5 252C 5C2
A1 1 1 1 1 x2 + y
2, z
2
A2 1 1 1 –1 z, Rz
E1 2 2 cos 72º
2 cos 144°
0 (x, y)(Rx, Ry) (xz, yz)
E2 2 2 cos 144º 2 cos 72
° 0 (x
2 – y
2, 2xy)
D6
(622)
E 2C6 2C3 C2 23C 23C
A1 1 1 1 1 1 1 x2 + y
2, z
2
A2 1 1 1 1 –1 –1 z, Rz
B1 1 –1 1 –1 1 –1
B2 1 –1 1 –1 –1 1
E1 2 1 –1 –2 0 0 (x, y)(Rx, Ry) (xz, yz)
E2 2 –1 –1 2 0 0 (x2 – y
2, 2xy)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 7
4. The Groups Cnν (n = 2, 3, 4, 5, 6)
C2ν
(2mm)
E C2 σν(xz) v (yz)
A1 1 1 1 1 z x2, y
2, z
2
A2 1 1 –1 –1 Rz xy
B1 1 –1 1 –1 x, Ry xz
B2 1 –1 –1 1 y, Rx yz
C3ν
(3m)
E 2C3 3σν
A1 1 1 1 z x2 + y
2, z
2
A2 1 1 –1 Rz
E 2 –1 0 (x, y)(Rx, Ry) (x2 – y
2, 2xy)(xz, yz)
C4ν
(4mm)
E 2C4 C2 2σν 2σd
A1 1 1 1 1 1 z x2 + y
2, z
2
A2 1 1 1 –1 –1 Rz
B1 1 –1 1 1 –1 x2 – y
2
B2 1 –1 1 –1 1 xy
E 2 0 –2 0 0 (x, y)(Rx, Ry) (xz, yz)
C5ν E 2C5 252C 5σν
A1 1 1 1 1 z x2 + y
2, z
2
A2 1 1 1 –1 Rz
E1 2 2 cos 72° 2 cos 144° 0 (x, y)(Rx, Ry) (xz, yz)
E2 2 2 cos 144° 2 cos 72° 0 (x2 – y
2, 2xy)
C6ν
(6mm)
E 2C6 2C3 C2 3σν 3σd
A1 1 1 1 1 1 1 z x2 + y
2, z
2
A2 1 1 1 1 –1 –1 Rz
B1 1 –1 1 –1 1 –1
B2 1 –1 1 –1 –1 1
E1 2 1 –1 –2 0 0 (x, y)(Rx, Ry) (xz, yz)
E2 2 –1 –1 2 0 0 (x2 – y
2, 2xy)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 8
5. The Groups Cnh (n = 2, 3, 4, 5, 6)
C2h
(2/m)
E C2 I σh
Ag 1 1 1 1 Rz x2, y
2, z
2, xy
Bg 1 –1 1 –1 Rx, Ry xz, yz
Au 1 1 –1 –1 z
Bu 1 –1 –1 1 x, y
C3h
6
E C3 23C σh S3
53S ε = exp (2πi/3)
A' 1 1 1 1 1 1 Rz x2 + y
2, z
2
E'
* *
* *
1 1
1 1
(x, y) (x2 – y
2, 2xy)
A'' 1 1 1 –1 –1 –1 z
E''
* *
* *
1 1
1 1
(Rx, Ry) (xz, yz)
C4h
(4/m)
E C4 C2 34C
i 34S σh S4
Ag 1 1 1 1 1 1 1 1 Rz x2 + y
2, z
2
Bg 1 –1 1 –1 1 –1 1 –1 (x2 – y
2, 2xy)
Eg
1 i 1 i 1 i 1 i
1 i 1 i 1 i 1 i
(Rx, Ry) (xz, yz)
Au 1 1 1 1 –1 –1 –1 –1 z
Bu 1 –1 1 –1 –1 1 –1 1
Eu
1 i 1 i 1 i 1 i
1 i 1 i 1 i 1 i
(x, y)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 9
5. The Groups Cnh (n = 2, 3, 4, 5, 6) (cont…)
C5h E C5 25C 3
5C 45C h S5 7
5S
35S 9
5S ε = exp(2i/5)
A 1 1 1 1 1 1 1 1 1 1 Rz x2+y
2, z
2
1E
2 *2 * 2 *2 *
** *2 2 *2 2
1 1
1 1
(x, y)
2E
2 * *2 2 * *2
*2 * 2 *2 * 2
1 1
1 1
z (x2 – y
2, 2xy)
A 1 1 1 1 1 –1 –1 –1 –1 –1
1E 2 *2 * 2 *2 *
** *2 2 *2 2
1 1
1 1
(Rx, Ry) (xz, yz)
2E 2 * *2 2 * *2
*2 * 2 *2 * 2
1 1
1 1
C6h
(6/m)
E C6 C3 C2 2
3C
5
6C
i 5
3S
5
6S h S6 S3 ε = exp(2i/6)
Ag 1 1 1 1 1 1 1 1 1 1 1 1 x2+y
2, z
2
Bg 1 –1 1 –1 1 –1 1 –1 1 –1 1 –1
E1g
* * * *
* ** *
1 1 1 1
1 1 1 1
(Rx, Ry) (xz, yz)
E2g
* * * *
** * *
1 1 1 1
1 1 1 1
(x2 – y
2, 2xy)
Au 1 1 1 1 1 1 –1 –1 –1 –1 –1 –1 Z
Bu 1 –1 1 –1 1 –1 –1 1 –1 1 –1 1
E1u
* * * *
* ** *
1 1 1 1
1 1 1 1
(x, y)
E2u
* * * *
** * *
1 1 1 1
1 1 1 1
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 10
6. The Groups Dnh (n = 2, 3, 4, 5, 6)
D2h
(mmm)
E C2(z) C2(y) C2(x) i (xy) (xz) (yz)
Ag 1 1 1 1 1 1 1 1 x2, y
2, z
2
B1g 1 1 –1 –1 1 1 –1 –1 Rz xy
B2g 1 –1 1 –1 1 –1 1 –1 Ry xz
B3g 1 –1 –1 1 1 –1 –1 1 Rx yz
Au 1 1 1 1 –1 –1 –1 –1
B1u 1 1 –1 –1 –1 –1 1 1 z
B2u 1 –1 1 –1 –1 1 –1 1 y
B3u 1 –1 –1 1 –1 1 1 –1 x
D3h
26 m
E 2C3 3C2 h 2S3 3v
1A 1 1 1 1 1 1 x2 + y
2, z
2
2A 1 1 –1 1 1 –1 Rz
E 2 –1 0 2 –1 0 (x, y) (x2 – y
2, 2xy)
1A 1 1 1 –1 –1 –1
2A 1 1 –1 –1 –1 1 z
E 2 –1 0 –2 1 0 (Rx, Ry) (xy, yz)
D4h
(4/mmm) E 2C4 C2
22C 22C
i 2S4 h 2v 2d
A1g 1 1 1 1 1 1 1 1 1 1 x2 + y
2, z
2
A2g 1 1 1 –1 –1 1 1 1 –1 –1 Rz
B1g 1 –1 1 1 –1 1 –1 1 1 –1 x2 – y
2
B2g 1 –1 1 –1 1 1 –1 1 –1 1 xy
Eg 2 0 –2 0 0 2 0 –2 0 0 (Rx, Ry) (xz, yz)
A1u 1 1 1 1 1 –1 –1 –1 –1 –1
A2u 1 1 1 –1 –1 –1 –1 –1 1 1 Z
B1u 1 –1 1 1 –1 –1 1 –1 –1 1
B2u 1 –1 1 –1 1 –1 1 –1 1 –1
Eu 2 0 –2 0 0 –2 0 2 0 0 (x, y)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 11
6. The Groups Dnh (n = 2, 3, 4, 5, 6) (cont…)
D5h E 2C5 2
52C
5C2 h 2S5 352S 5v
1A 1 1 1 1 1 1 1 1 x2 + y
2, z
2
2A 1 1 1 –1 1 1 1 –1 Rz
1E 2 2 cos 72 2 cos 144 0 2 2 cos 72 2 cos 144 0 (x, y)
2E 2 2 cos 144 2 cos 72 0 2 2 cos 144 2 cos 72 0 (x2 – y
2, 2xy)
1A 1 1 1 1 –1 –1 –1 –1
2A 1 1 1 –1 –1 –1 –1 1 z
1E 2 2 cos 72 2 cos 144 0 –2 –2 cos 72 –2 cos 144 0 (Rx, Ry) (xy, yz)
2E 2 2 cos 144 2 cos 72 0 –2 –2 cos 144 –2 cos 72 0
D6h
(6/mmm)
E 2C6 2C3 C2 23C 23C
i 2S3 2S6 h 3d 3v
A1g 1 1 1 1 1 1 1 1 1 1 1 1 x2 + y
2, z
2
A2g 1 1 1 1 –1 –1 1 1 1 1 –1 –1 Rz
B1g 1 –1 1 –1 1 –1 1 –1 1 –1 1 –1
B2g 1 –1 1 –1 –1 1 1 –1 1 –1 –1 1
E1g 2 1 –1 –2 0 0 2 1 –1 –2 0 0 (Rx – Ry) (xz, yz)
E2g 2 –1 –1 2 0 0 2 –1 –1 2 0 0 (x2 – y
2, 2xy)
A1u 1 1 1 1 1 1 –1 –1 –1 –1 –1 –1
A2u 1 1 1 1 –1 –1 –1 –1 –1 –1 1 1 z
B1u 1 –1 1 –1 1 –1 –1 1 –1 1 –1 1
B2u 1 –1 1 –1 –1 1 –1 1 –1 1 1 –1
E1u 2 1 –1 –2 0 0 –2 –1 1 2 0 0 (x, y)
E2u 2 –1 –1 2 0 0 –2 1 1 –2 0 0
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 12
7. The Groups Dnd (n = 2, 3, 4, 5, 6)
D2d = Vd
42m
E 2S4 C2 22C
2d
A1 1 1 1 1 1 x2 + y
2, z
2
A2 1 1 1 –1 –1 Rz
B1 1 –1 1 1 –1 x2 – y
2
B2 1 –1 1 –1 1 z xy
E 2 0 –2 0 0 (x, y)
(Rx, Ry)
(xz, yz)
D3d
(3)m
E 2C3 3C2 i 2S6 3d
A1g 1 1 1 1 1 1 x2 + y
2, z
2
A2g 1 1 –1 1 1 –1 Rz
Eg 2 –1 0 2 –1 0 (Rx, Ry) (x2 – y
2, 2xy)
(xz, yz)
A1u 1 1 1 –1 –1 –1
A2u 1 1 –1 –1 –1 1 z
Eu 2 –1 0 –2 1 0 (x, y)
D4d E 2S8 2C4 3
82S
C2 24C
4d
A1 1 1 1 1 1 1 1 x2 + y
2, z
2
A2 1 1 1 1 1 –1 –1 Rz
B1 1 –1 1 –1 1 1 –1
B2 1 –1 1 –1 1 –1 1 z
E1 2 2 0
– 2 –2 0 0 (x, y)
E2 2 0 –2 0 2 0 0 (x2 – y
2, 2xy)
E3 2 – 2
0 2 –2 0 0 (Rx, Ry) (xz, yz)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 13
7. The Groups Dnd (n = 2, 3, 4, 5, 6) (cont..)
D5d E 2C5 2
52C
5C2 i 3
102S 2S10 5d
A1g 1 1 1 1 1 1 1 1 x2 + y
2, z
2
A2g 1 1 1 –1 1 1 1 –1 Rz
E1g 2 2 cos 72 2 cos 144 0 2 2 cos 72 2 cos 144 0 (Rx, Ry) (xy, yz)
E2g 2 2 cos 144 2 cos 72 0 2 2 cos 144 2 cos 72 0 (x2 – y
2, 2xy)
A1u 1 1 1 1 –1 –1 –1 –1
A2u 1 1 1 –1 –1 –1 –1 1 z
E1u 2 2 cos 72 2 cos 144 0 –2 –2 cos 72 –2 cos 144 0 (x, y)
E2u 2 2 cos 144 2 cos 72 0 –2 –2 cos 144 –2 cos 72 0
D6d E 2S12 2C6 2S4 2C3 5
122S
C2 26C
6d
A1 1 1 1 1 1 1 1 1 1 x2 + y
2, z
2
A2 1 1 1 1 1 1 1 –1 –1 Rz
B1 1 –1 1 –1 1 –1 1 1 –1
B2 1 –1 1 –1 1 –1 1 –1 1 z
E1 2 3 1 0 –1
– 3 –2 0 0 (x, y)
E2 2 1 –1 –2 –1 1 2 0 0 (x2 – y
2, 2xy)
E3 2 0 –2 0 2 0 –2 0 0
E4 2 –1 –1 2 –1 –1 2 0 0
E5 2 – 3
1 0 –1 3 –2 0 0 (Rx, Ry) (xy, yz)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 14
8. The Groups Sn (n = 4, 6, 8)
S4
(4)
E S4 C2 3
4S
A 1 1 1 1 Rz x2 + y
2, z
2
B 1 –1 1 –1 z (x2 – y
2, 2xy)
E 1 i 1 i
1 i 1 i
(x, y) (Rx, Ry) (xz, yz)
S6
(3)
E C3 2
3C
i 5
6S
S6 = exp (2i/3)
Ag 1 1 1 1 1 1 Rz x2 + y
2, z
2
Eg
* *
* *
1 1
1 1
(Rx, Ry) (x2 – y
2, 2xy) (xy, yz)
Au 1 1 1 –1 –1 –1 z
Eu
* *
* *
1 1
1 1
(x, y)
S8 E S8 C4 3
8S
C2 5
8S
3
4C 7
8S
= exp (2i/8)
A 1 1 1 1 1 1 1 1 Rz x2 + y
2, z
2
B 1 –1 1 –1 1 –1 1 –1 z
E1
* *
* *
1 i 1 i
1 i 1 i
(x, y)
E2
1 i 1 i 1 i 1 i
1 i 1 i 1 i 1 i
(x2 – y
2, 2xy)
E3
* *
* *
1 i 1 i
1 i 1 i
(Rx, Ry) (xy, yz)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 15
9. The Cubic Groups
T
(23)
E 4C3 2
34C
3C2 = exp (2i/3)
A 1 1 1 1 x2 + y
2 + z
2
E
*
*
1 1
1 1
( 3 (x2 – y
2)2z
2 – x
2 – y
2)
T 3 0 0 –1 (x, y, z)
(Rx, Ry, Rz)
(xy, xz, yz)
Td
(43 )m
E 8C3 3C2 6S4 6d
A1 1 1 1 1 1 x2 + y
2 + z
2
A2 1 1 1 –1 –1
E 2 –1 2 0 0 (2z2 – x
2 – y
2, 3 (x
2 – y
2)
T1 3 0 –1 1 –1 (Rx, Ry, Rz)
T2 3 0 –1 –1 1 (x, y, z) (xy, xz, yz)
Th
(m3)
E 4C3 2
34C
3C2 i 4S6 5
64S 3d = exp (2i/3)
Ag 1 1 1 1 1 1 1 1 x2 + y
2 + z
2
Eg
* *
* *
1 1 1 1
1 1 1 1
(2z
2 – x
2 –y
2,
3 (x2 – y
2)
Tg 3 0 0 –1 3 0 0 –1 (Rx, Ry, Rz) (xy, yz, xz)
Au 1 1 1 1 –1 –1 –1 –1
Eu
* *
* *
1 1 1 1
1 1 1 1
Tu 3 0 0 –1 –3 0 0 1 (x, y, z)
O
(432)
E 8C3 3C2 6C4 26C
A1 1 1 1 1 1 x2 + y
2 + z
2
A2 1 1 1 –1 –1
E 2 –1 2 0 0 (2z2 – x
2 – y
2,
3 (x2 – y
2))
T1 3 0 –1 1 –1 (x, y, z)
(Rx, Ry, Rz)
T2 3 0 –1 –1 1 (xy, xz, yz)
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 16
9. The Cubic Groups (cont…)
Oh
(m3m)
E 8C3 6C2 6C4 3C2 2
4( )C
i 6S4 8S6 3h 6d
A1g 1 1 1 1 1 1 1 1 1 1 x2 + y
2 + z
2
A2g 1 1 –1 –1 1 1 –1 1 1 –1
Eg 2 –1 0 0 2 2 0 –1 2 0 (2z2 – x
2 –y
2,
3 (x2 – y
2))
T1g 3 0 –1 1 –1 3 1 0 –1 –1 (Rx, Ry, Rz)
T2g 3 0 1 –1 –1 3 –1 0 –1 1 (xy, xz, yz)
A1u 1 1 1 1 1 –1 –1 –1 –1 –1
A2u 1 1 –1 –1 1 –1 1 –1 –1 1
Eu 2 –1 0 0 2 –2 0 1 –2 0
T1u 3 0 –1 1 –1 –3 –1 0 1 1 (x, y, z)
T2u 3 0 1 –1 –1 –3 1 0 1 –1
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 17
10. The Groups I, Ih
I E 12C5 2
512C 20C3 15C2 1
21
21 5
A 1 1 1 1 1 x2+y
2+z
2
T1 3 +
0 –1 (x, y, z)
(Rx, Ry, Rz)
T2 3
+ 0 –1
G 4 –1 –1 1 0
H 5 0 0 –1 1 (2z2 – x
2 – y
2,
3 (x2 – y
2)
xy, yz, zx)
Ih E 12C5 2
512C 20C3 15C2 i 12S10
3
1012S 20S6 15 1
21
21 5
Ag 1 1 1 1 1 1 1 1 1 1 x2 + y
2 + z
2
T1g 3 +
0 –1 3
+ 0 –1 (Rx,Ry,Rz)
T2g 3
+ 0 –1 3
+
0 –1
Gg 4 –1 –1 1 0 4 –1 –1 1 0
Hg 5 0 0 –1 1 5 0 0 –1 1 (2z2 – x
2 – y
2,
3 (x2 – y
2))
(xy, yz, zx)
Au 1 1 1 1 1 –1 –1 –1 –1 –1
T1u 3 +
0 –1 –3
+ 0 1 (x, y, z)
T2u 3
+ 0 –1 –3
+
0 1
Gu 4 –1 –1 1 0 –4 1 1 –1 0
Hu 5 0 0 –1 1 –5 0 0 1 –1
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 18
11. The Groups Cv and Dh
Cv E 2C
… v
A1+ 1 1 … 1 z x
2 + y
2, z
2
A2– 1 1 … –1 Rz
E1 2 2 cos … 0 (x,y) (Rx,Ry) (xz, yz)
E2 2 2 cos 2 … 0 (x2 – y
2, 2xy)
E3 2 2 cos 3 … 0
… … … … …
… … … … …
Dh E 2C
v i 2S
… C2
g
1 1 … 1 1 1 … 1 x2 + y
2, z
2
g
1 1 … –1 1 1 … –1 Rz
g 2 2 cos … 0 2 –2 cos … 0 (Rx, Ry) (xz, yz)
g 2 2 cos 2 … 0 2 2 cos 2 … 0 (x2 – y
2, 2xy)
… … … … … … … … …
u
1 1 … 1 –1 –1 … –1 z
u
1 1 … –1 –1 –1 … 1
u 2 2 cos … 0 –2 2 cos … 0 (x,y)
u 2 2 cos 2 … 0 –2 –2 cos 2 … 0
… … … … … … … … …
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 19
12. The Full Rotation Group (SU2 and R3)
( )
1sin
20
( ) 1sin
2
2 +1 0
j
j
j
Notation : Representation labelled (j)
with j = 0,1/2, 1, 3/2,…, for R3 j is confined to integral
values (and written l or L) and the labels S (0)
, P (1)
, D (2)
, etc. are used.
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 20
Direct Products
1. General rules
(a) For point groups in the lists below that have representations A, B, E, T without subscripts, read
A1 = A2 = A, etc.
(b)
g u
g g u
u g
(c) Square brackets [ ] are used to indicate the representation spanned by the antisymmetrized
product of a degenerate representation with itself.
Examples
For D3h E E 1A +
2A + E
For D6h E1g E2g = 2Bg + E1g.
2. For C2, C3, C6, D3, D6,C2v,C3v, C6v,C2h, C3h, C6h, D3h, D6h, D3d, S6
A1 A2 B1 B2 E1 E2
A1 A1 A2 B1 B2 E1 E2
A2 A1 B2 B1 E1 E2
B1 A1 A2 E2 E1
B2 A1 E2 E1
E1 A1 + [A2]+ E2 B1 + B2 + E1
E2 A1 + [A2] + E2
3. For D2 , D2h
A B1 B2 B3
A A B1 B2 B3
B1 A B3 B2
B2 A B1
B3 A
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 21
4. For C4, D4, C4v, C4h, D4h, D2d, S4
A1 A2 B1 B2 E
A1 A1 A2 B1 B2 E
A2 A1 B2 B1 E
B1 A1 A2 E
B2 A1 E
E A1 + [A2] +B1 + B2
5. For C5, D5, C5v, C5h, D5h, D5d
A1 A2 E1 E2
A1 A1 A2 E1 E2
A2 A1 E1 E2
E1 A1 + [A2] + E2 E1 + E2
E2 A1 + [A2] + E1
6. For D4d, S8
A1 A2 B1 B2 E1 E2 E3
A1 A1 A2 B1 B2 E1 E2 E3
A2 A1 B2 B1 E1 E2 E3
B1 A1 A2 E3 E2 E1
B2 A1 E3 E2 E1
E1 A1 + [A2] + E2 E1 + E2 B1 + B2 + E2
E2 A1 + [A2] +
B1 + B2
E1 + E3
E3 A1 + [A2] + E2
7. For T, O, Th, Oh, Td
A1 A2 E T1 T2
A1 A1 A2 E T1 T2
A2 A1 E T2 T1
E A1 + [A2] + E T1 + T2 T1 + T2
T1 A1 + E + [T1] + T2 A2 + E + T1 + T2
T2 A1 + E + [T1] +
T2
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 22
8. For D6d
A1 A2 B1 B2 E1 E2 E3 E4 E5
A1 A1 A2 B1 B2 E1 E2 E3 E4 E5
A2 A1 B2 B1 E1 E2 E3 E4 E5
B1 A1 A2 E5 E4 E3 E2 E1
B2 A1 E5 E4 E3 E2 E1
E1 A1 + [A2] +
E2 E1 + E3 E2 + E4 E3 + E5 B1 + B2 +
E4
E2 A1 + [A2]
+ E4
E1 + E5 B1 + B2 +
E2
E3 + E5
E3 A1 + [A2] +
B1 + B2
E1 + E5 E2 + E4
E4 A1 + [A2]
+ E4 E1 + E3
E5 A1 + [A2]
+ E2
9. For I, Ih
A T1 T2 G H
A A T1 T2 G H
T1 A + [T1] +
H
G + H T2 + G + H T1 +T2 + G + H
T2 A + [T2] + H T1 + G + H T1 +T2 + G + H
G A + [T1 +T2]
+ G + H
T1 +T2 + G + 2H
H A1 + [T1 +T2 + G] +
G + 2H
10. For Cv, Dh
+
–
+
+
–
–
+
+
+ [–]
+
+
+
+ [–] +
:
Notation
…
= 0 1 2 3 4 …
1 2 = | 1 – 2 | + (1 + 2)
= +
+ [–] + (2).
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 23
11. The Full Rotation Group (SU2 and R3)
(j)
(j′)
= (j + j′)
+ (j + j′–1)
+ … + (|j–j′|)
(j)
(j)
= (2j)
+ (2j – 2)
+ … + (0)
+ [(2j – 1)
+ … + (1)
]
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 24
Extended rotation groups (double groups):
Character tables and direct product tables
*
2D E R 2C2(z) 2C2(y) 2C2(x)
E1/2 2 –2 0 0 0
*
3D E R 2C3 2C3R 3C2 3C2R
E1/2 2 –2 1 –1 0 0
E3/2 1 1 1 1 i i
1 1 1 1 i i
D4 E R 2C4 2C4R 2C2 24C 24C
E1/2 2 –2 2 – 2 0 0 0
E3/2 2 –2 – 2 2 0 0 0
*
6D E R 2C6 2C6R 2C3 2C3R 2C2 26C
26C
E1/2 2 –2 3 – 3 1 –1 0 0 0
E3/2 2 –2 – 3 3 –1 1 0 0 0
E5/2 2 –2 0 0 –2 2 0 0 0
*
dT E R 8C3 8C3R 6C2 6S4 6S4R
d12
*O E R 8C3 8C3R 6C2 6C4 6S4R 212C
E1/2 2 –2 1 –1 0 2 – 2 0
E5/2 2 –2 1 –1 0 – 2 2 0
G3/2 4 –4 –1 1 0 0 0 0
E1/2 E1/2 = [A] +B1 +B2 + B3
E1/2 E3/2
E1/2 [A1] + A2 + E 2E
E3/2 [A1] + A1 + 2A2
E1/2 E3/2
E1/2 [A1] + A2 + E B1 + B2 + E
E3/2 [A1] + A2 + E
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 25
E1/2 E3/2 E5/2
E1/2 [A1] +A2 + E1 B1 + B2+ E2 E1 + E2
E3/2 [A1] +A2 + E1 E1 + E2
E5/2 [A1] + A2 +B1 + B2
E1/2 E5/2 E3/2
E1/2 [A1] + T1 A2 + T2 E + T1 + T2
E5/2 [A1] + T1 E + T1 + T2
G3/2 [A1 + E + T2] + A2 + 2T1 + T2]
Direct products of ordinary and extended representations for *dT and O*
A1 A2 E T1 T2
E1/2 E1/2 E5/2 G3/2 E1/2 + G3/2 E5/2 + G3/2
E5/2 E5/2 E1/2 G3/2 E5/2 + G3/2 E1/2 + G3/2
G3/2 G3/2 G3/2 E1/2 + E5/2+ G3/2 E1/2 + E5/2+ 2G3/2 E1/2 + E5/2+ 2G3/2
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 26
Descent in symmetry and subgroups
The following tables show the correlation between the irreducible representations of a group
and those of some of its subgroups. In a number of cases more than one correlation exists
between groups. In Cs the of the heading indicates which of the planes in the parent group
becomes the sole plane of Cs; in C2v it becomes must be set by a convention); where there are
various possibilities for the correlation of C2 axes and planes in D4h and D6h with their
subgroups, the column is headed by the symmetry operation of the parent group that is
preserved in the descent.
C2v C2 Cs
(zx)
Cs
(yz)
A1 A A A
A2 A A" A"
B1 B A A
B2 B A" A"
C3v C3 Cs
A1 A A
A2 A A"
E E A A+ "
C4v C2v
v
C2v
d
A1 A1 A1
A2 A2 A2
B1 A1 A2
B2 A2 A1
E 1 2B B+ 1 2B B+
[Other subgroups: C4, C2, C6]
D3h
C3h
C3v
C2
h
Cs
h
Cs
1A A A1 A1 A A
2A A A2 B2 A A"
E' E' E A1 + B2 2A' A A' + "
1A A" A2 A2 A" A"
2A A" A1 B1 A" A
E" E" E A2 + B1 2A" A A' + "
[Other subgroups: D3, C3, C2]
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 27
D4h 2d
2 2( )
D
C C 2d
2 2( )
D
C C 2h
2
D
C 2h
2
D
C 2
2
D
C 2
2
D
C
C4h C4v C2v
C2, σv
C2v
C2, σd
A1g A1 A1 Ag Ag A A Ag A1 A1 A1
A2g A2 A2 B1g B1g B1 B1 Ag A2 A2 A2
B1g B1 B2 Ag B1g A B1 Bg B1 A1 A2
B2g B2 B1 B1g Ag B1 A Bg B2 A2 A1
Eg E E B2g + B3g B2g + B3g B2 + B3 B2 + B3 Eg E B1 + B2 B1 + B2
A1u B1 B1 Au Au A A Au A2 A2 A2
A2u B2 B2 B1u B1u B1 B1 Au A1 A1 A1
B1u A1 A2 Au B1u A B1 Bu B2 A2 A1
B2u A2 A1 B1u Au B1 A Bu B1 A1 A2
Eu E E B2u + B3u B2u + B3u B2 + B3 B2 + B3 Eu E B1 + B2 B1 + B2
Other subgroups:D4, C4, S4, 3C2h, 3Cs,3C2,Ci, (2C2v)
D6 3d 2D C 3d 2D C D2h
σh → σ(xy)
σv → σ(yz)
C6v C3v
σv
C2v
2C
C2v
2C
C2h
C2
C2h
2C
C2h
2C
A1g A1g A1g Ag A1 A1 A1 A1 Ag Ag Ag
A2g A2g A2g B1g A2 A2 B1 B1 Ag Bg Bg
B1g A2g A1g B2g B2 A2 A2 B2 Bg Ag Bg
B2g A1g A2g B3g B1 A1 B2 A2 Bg Bg Ag
E1g Eg Eg B2g + B3g E1 E A2 + B2 A2 + B2 2Bg Ag + Bg Ag + Bg
E2g Eg Eg Ag + B1g E2 E A1 + B1 A1 + B1 2Ag Ag + Bg Ag + Bg
A1u A1u A1g Au A2 A2 A2 A2 Au Au Au
A2u A2u A2g B1u A1 A1 B2 B2 Au Bu Bu
B1u A2u A1u B2u B1 A1 B1 B1 Bu Au Bu
B2u A1u A2u B3u B2 A2 A1 A1 Bu Bu Au
E1u Eu Eu B2u + B3u E1 E A1 + B1 A1 + B1 2Bu Au + Bu Au + Bu
E2u Eu Eu Au + B1u E2 E A2 + B2 A2 + B2 2Au Au + Bu Au + Bu
Other subgroups: D6, 2D3h, C6h, C6, C3h, 2D3, S6, D2, C3, 3C2, 3Cg, Ci
Td T D2d C3v C2v
A1 A A1 A1 A1
A2 A B1 A2 A2
E E A1 + B1 E A1 +A2
T1 T A2 + E A2 + E A2 + B1 + B2
T2 T B2 + E A1 + E A1 + B2 + B1
Other subgroups: S4, D2, C3, C2, Cs.
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 28
Oh O Td Th D4h D3d
A1g A1 A1 Ag A1g A1g
A2g A2 A2 Ag B1g A2g
Eg E E Eg A1g + B1g Eg
T1g T1 T1 Tg A2g + Eg A2g + Eg
T2g T2 T2 Tg B2g + Eg A1g + Eg
A1u A1 A2 Au A1u A1u
A2u A2 A1 Au B1u B1u
Eu E E Eu A1u + B1u Eu
T1u T1 T2 Tu A2u + Eu A2u + Eu
T2u T2 T1 Tu B2u + Eu A1u + Eu
Other subgroups: T, D4, D2d, C4h, C4v, 2D2h, D3, C3v, S6, C4, S4, 3C2v, 2D2, 2C2h, C3, 2C2, S2, Cs
R3 O D4 D3
S A1 A1 A1
P T1 A2 + E A2 + E
D E + T2 A1 + B1 +B2 + E A1 + 2E
F A2 + T1 +T2 A2+ B1 +B2 + 2E A1 + 2A2 + 2E
G A1 + E + T1 + T2 2A1 + A2 +B1 + B2 + 2E 2A1+ A2 + 3E
H E + 2T1 + T2 A1 + 2A2 + B1 + B2 + 3E A1 + 2A2 + 4E
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 29
Notes and Illustrations
General Formulae
(a) Notation
h the order (the number of elements) of the group.
Γ(i)
labels the irreducible representation.
Χ(i)
(R) the character of the operation R in Γ(i).
( ) ( )iD R
the μv element of the representative matrix of the operation R in the irreducible
representation Γ(i).
li the dimension of Γ
(i).(the number of rows or columns in the matrices D
(i))
(b) Formulae
(i) Number of irreducible representations of a group = number of classes.
(ii) 2l hii
(iii)
( ) ( )( ) ( )i iR D R
(iv) Orthogonality of representations: ( ) ( )*( ) ( ) ( / )i i'
i' ' ii' ' 'D R D R h l
(ij=1 if i = j and ij = 0 if i j
(v) Orthogonality of characters: ( ) ( )*( ) ( )i i
ii'R
R R h
(vi) Decomposition of a direct product, reduction of a representation: If
( )i
i
i
a
and the character of the operation R in the reducible representation is (R), then the coefficients at
are given by ( ) *( / ) ( ) ( ).i
iR
a l h R R
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 30
(vii) Projection operators:
The projection operator ( ) ( ) *( / ) ( )i i
iR
l h R R P
when applied to a function f, generates a sum of functions that constitute a component of a
basis for the representation Γ(i)
; in order to generate the complete basis P (i)
must be applied
to li distinct functions f. The resulting functions may be made mutually orthogonal. When li
= 1 the function generated is a basis for Γ(i)
without ambiguity: ( ) ( )i if fP
(viii) Selection rules:
If f(i)
is a member of the basis set for the irreducible representation Γ(i)
, f{k)
a member of that
for Γ(k)
, and ̂ (j) an operator that is a basis for Γ
(j), then the integral
( )* ( ) ( )ˆi j kd f f is zero unless Γ
(i) occurs in the decomposition of the direct product Γ
(j) Γ
(k)
(ix) The symmetrized direct product is written ( ) ( )
si i , and its characters are given by
( ) ( ) ( ) ( )2 21 12 2
( ) ( ) ( ) ( )i i i is
R R R R
The antisymmetrized direct product is written ( ) ( )
ai i and its characters are given by
( ) ( ) ( ) ( )2 21 12 2
( ) ( ) ( ) ( )i i i ia
R R R R
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 31
Worked examples
1. To show that the representation Γ based on the hydrogen 1s-orbitals in NH3 (C3v) contains A1
and E, and to generate appropriate symmetry adapted combinations.
A table in which symmetry elements in the same class are distinguished will be employed:
C3v E 3C
–
3C 1 2 3
A1 1 1 1 1 1 1
A2 1 1 1 –1 –1 –1
E 2 –1 –1 0 0 0
D(R) 1 0 0
0 1 0
0 0 1
0 0 1
1 0 0
0 1 0
0 1 0
0 0 1
1 0 0
1 0 0
0 0 1
0 1 0
0 0 1
0 1 0
1 0 0
0 1 0
1 0 0
0 0 1
x(R) 3 0 0 1 1 1
Rh1 h1 h2 h3 h1 h3 h2
Rh2 h2 h3 h1 h3 h2 h1
The representative matrices are derived from the effect of the operation R on the basis (h1, h2,
h3); see the figure below. For example
3 1 2 3 2 3 1 1 2 3
0 0 1
( , , ) ( , , ) ( , , ) 1 0 0
0 1 0
C h h h h h h h h h
According to the general formula (b)(iii) the character (R) is the sum of the diagonal elements
of D(R). For example, (2) = 0 + 1 + 0 = 1. The decomposition of Γ follows from the formula
(b)(vi):
Γ = a1A1 + a2A2 + aEE
where
11 6
12 6
16
1 3 2 1 0 3 1 1 1
1 3 2 1 0 3 1 (–1) 0
2 3 2 (–1) 0 3 0 1 1E
a
a
a
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 32
Therefore
Γ = A1 + E
Symmetry adapted combinations are generated by the projection operator in (b)(vii). Using the
last two rows of the table,
( ) 11
1 1 1 2 36
13 2 1 2 33
( ) 21 1 2 3 16
13 2 1 2 33
( ) 22 2 3 1 36
12 1 1 2 33
( ) (1 1 1 11
1 1 ) ( )
( ) (2 –1 –1 0
0 0 ) (2 – – )
( ) (2 –1 –1 0
0 0 ) (– 2 – )
A
E
E
A h h h h h
h h h h h
E h h h h h
h h h h h
E h h h h h
h h h h h
(E) and '(E) provide a valid basis for the E representation, but the orthogonal combinations
1 1
2 21 2 3
1 1
2 22 3
( ) (1/6) (2 – – ) (3/ 2) ( )
( ) (1/ 2) ( – ) (1/ 2) ( ) 2 ( )
a
b
E h h h E
E h h E ' E
would be a more useful basis in most applications.
2. To determine the symmetries of the states arising from the electronic configurations e2 and e
1t2
1
for a tetrahedral complex (Td ), and to determine the group theoretical selection rules for electric
dipole transitions between them.
The spatial symmetries of the required states are given by the direct products in Table 7.
E E = A1 + [A2] + E E T2 = T1 + T2
Combination of the electron spins yields both singlet and triplet states, but for the e2
configuration some possibilities are excluded. Since the total (spin and orbital) state must be
antisymmetric under electron interchange, the antisymmetrized spatial combination [A2] must be
a triplet, and the symmetrized combinations A1 and E are singlets. For the e1t2
1 configuration
there are no exclusions. The required terms are therefore
e2
1A1 +
3A2 +
1E
e1t2
1
1T1 +
1T2 +
3T1 +
3T2
The selection rules are obtained from formula (b)(viii). For electric dipole transitions the operator
(j)
has the symmetry of a vector (x, y, z), which from the character table for Td transforms as T2.
From the table of direct products, Table 7,
A1 T2 = T2 A2 T1 = T2 E T2 = E T1 = T1 + T2
Assuming the spin selection rule S = 0, the allowed transitions are
e2 1A1 e
1t2
1 1T2 e
2 3A2 e
1t2
1
3T1 e
2 1E e
1t2
1
1T1,
1T2
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 33
3. To determine the symmetries of the vibrations of a tetrahedral molecule AB4, and to predict the
appearance of its infrared and Raman spectra.
The molecule is depicted in the figure below and the character table for the point group Td is
given on page 15.
The representations spanned by the vibrational coordinates are based on the 5 3 cartesian
displacements less the representations T1 and T2, which are accounted for by the rotations (Rx, Ry,
Rz) and the translations (x, y, z). The stretching vibrations are the subset based on the 4 bonds of
the molecule. For a particular symmetry operation, only atoms (or bonds) that remain invariant
can contribute to the character of the cartesian displacement representation, Γ (all)
(or the
stretching representation, Γ(stretch)
).
C3: Two atoms invariant, x, y, z, interchanged (all)(C3) = 0
One bond invariant (stretch)(C3) = 1
C2(z): Central atom invariant; x, y, sign reversed, z invariant (all)
(C3) = 0
No bonds invariant (stretch) (C2) = 0
S4(z): Central atom invariant; x, y, interchanged, z sign reversed x(all)
(S4) = – 1
No bonds invariant (stretch)(S4) = 0
d(z): Three atoms invariant; x, y, interchanged, z invariant x (all)
(d) = 3
Two bonds invariant (stretch)(d) = 2
The characters of the representations (all)
and (stretch)
are therefore
E 8C3 3C2 6S4 6d
(all) 15 0 –1 –1 3 = = A1 + E + T1 + 3T2
(stretch) 4 1 0 0 2 = A1 + T2
(alI)
and (stretch)
have been decomposed with the help of formula (b)(vi) (compare Example 1).
Allowing for the rotations and translations contained in (all)
there are therefore four fundamental
vibrations, conventionally labelled 1 (A1), 2(E), 3(T2), and 4(T2). 1 and v2 are stretching and
bending vibrations respectively, 3 and 4 involve both stretching and bending motions.
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 34
The selection rule (b)(viii) gives the spectroscopic properties of the vibrations. Infrared activity
is induced by the dipole moment (a vector with symmetry T2, according to the character table for
Td) as the operator ˆ j
In the case of the Raman effect, ˆ j
is the component of the
polarizability tensor (A1 + E + T2). f(i)
is the ground vibrational state (A1), and f(k)
is the excited
state (with the same symmetry as the vibration in the case of the fundamental; as the direct
product of the appropriate representations in the case of an overtone or a combination band).
v1(A1)and v2(E) are therefore Raman active and 3(T2) and 4(T2) are infrared and Raman active.
The following overtone and combination bands are allowed in the infrared spectrum:
1 + 3, 1 + 4, 2 + 3 , 2 + 4, 23 , 3 + 4, 24
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 35
Examples of bases for some representations
The customary bases—polar vector (e.g. translation x), axial vector (e.g. rotation Rx), and tensor
(e.g. xy)—are given in the character tables.
It may be of some assistance to consider other types of bases and a few examples are given here.
Base Irreducible Representation
1
A2 in Td
2 x(1)y(2) – x(2)y(1) A2 in C4v
3 The normal vibration of an octahedral molecule
represented by
Alg in Oh
4
The three equivalent normal vibrations of an
octahedral molecule, one of which is represented by
T2u in Oh
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 36
5 The -orbital of the benzene molecule represented by
A2u in D6h
6 The -orbital of the benzene molecule represented by
B2g in D6h
7
The -orbital of the naphthalene molecule
represented by
Au in D2h
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 37
Illustrative Examples of Point Groups
I Shapes
The character tables for (a), Cn, are on page 4; for (b), Dn, on page 6; for (c), Cnv, on page 7; for
(d), Cnh, on page 8; for (e), Dnh, on page 10; for (f), Dnd, on page 12; and for (g), S2n, on page 14.
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 38
Cs Ci
.
Td Oh
tetrahedron cube
Oh Ih
octahedron dodecahedron
Ih R3
icosahedron sphere
The character table for Cs is on page 3, for Ci on page 3, for Td on page 15, for Oh on page 16, for
Ih on page 17, and for R3 on page 19.
Atkins, Child, & Phillips: Tables for Group Theory
H i g h e r E d u c a t i o n
© Oxford University Press, 2008. All rights reserved. 39
II Molecules
Point
group
Example Page number
for character
table
C1 CHFClBr 3
Cs BFClBr (planar), quinoline 3
Ci meso-tartaric acid 3
C2 H2O2, S2C12 (skew) 4
C2v H2O, HCHO, C6H5C1 7
C3v NH3 (pyramidal), POC13 7
C4v SF5Cl, XeOF4 7
C2h trans-dichloroethylene 8
C3h
(in planar configuration)
8
D2h trans-PtX2Y2, C2H4 10
D3h BF3 (planar), PC15 (trigonal bipyramid), 1:3: 5–trichlorobenzene 10
D4h AuCl4– (square plane) 10
D5h ruthenocene (pentagonal prism), IF7 (pentagonal bipyramid) 11
D6h benzene 11
D2d CH2=C=CH2 12
D4d S8 (puckered ring) 12
D5d ferrocene (pentagonal antiprism) 13
S4 tetraphenylmethane 14
Td CCl4 15
Oh SF6, FeF63–
16
Ih B12H122–
17
Cv HCN, COS 18
Dh CO2, C2H2 18
R3 any atom (sphere) 19